TRAFFIC NOISE MONITORING IN THE CITY OF MILAN: CONSTRUCTION OF A REPRESENTATIVE STATISTICAL COLLECTION OF ACOUSTIC TRENDS

In the context of the European project DYNAMAP, a campaign of acoustic monitoring of road traffic noise was realized in the entire area of the city of Milan. The operations involve the collection of temporal trends of noise levels in order to create a statistically significant sample for post-processing analysis. The monitoring activities encompass the following steps: collection and selection of previous noise data concerning the road sources; identification and selection of monitoring sites based on specific criteria such as road geometric characteristics, the functional road classification (A, D, E, F), the type of traffic, the absence of other noise sources, etc.; acquisition of the acoustic data by weekday using various types of units for the long-term noise monitoring; correlation of acoustic data with weather data and deletion of data when levels of rainfall and wind speed exceeding threshold values; identification and removal of abnormal events through sonogram analysis; acquisition of series of equivalent sound levels, measured on different time intervals: 5, 10, 15, 20, 30 and 60 minutes; acquisition of traffic flow data related to road stretches, via statistical modeling or on-site measurements. All acquired data are stored in a geodatabase useful for further processing, such as cluster analysis and the development of an acoustic model for the city of Milan. The acquisition of noise data will also provide useful indications to size a monitoring network of low-cost sensors, one of the main target of the DYNAMAP project.